| TIAGABINE HYDROCHLORIDE
Classifications: anticonvulsant; gaba inhibitor; Therapeutic: anticonvulsant
Prototype: Valproic acid sodium (sodium valproate)
Pregnancy Category: C
2 mg, 4 mg, 12 mg, 16 mg, 20 mg tablets
GABA inhibitor for the treatment of partial epilepsy. Potent and selective inhibitor of GABA uptake into presynaptic neurons;
allows more GABA to bind to the surfaces of postsynaptic neurons in the CNS.
Effectiveness indicated by reduction in seizure activity.
Adjunctive therapy for partial seizures.
Hypersensitivity to tiagabine; pregnancy (category C); lactation; children <12 y.
Liver function impairment; history of spike and wave discharge on EEG; status epilepticus.
Route & Dosage
Adult: PO Start with 4 mg q.d., may increase dose by 48 mg/d qwk (max: 56 mg/d in 24 divided doses)
Adolescent (1218 y): PO Start with 4 mg q.d., after 2 wk may increase dose by 48 mg/d qwk (max: 32 mg/d in 24 divided doses)
- Give with food.
- Make dosage increases, when needed, at weekly intervals.
- Store at 15°30° C (59°86° F) in a tightly closed container and protect from light.
Adverse Effects (≥1%)Body as a Whole:
Infection, flu-like syndrome, pain, myasthenia, allergic reactions, chills, malaise, arthralgia. CNS: Dizziness, asthenia, tremor, somnolence, nervousness,
difficulty concentrating, ataxia, depression
, abnormal gait, hostility, confusion, speech disorder, difficulty
with memory, paresthesias, emotional lability, agitation, dysarthria, euphoria, hallucinations, hyperkinesia, hypertonia,
hypotonia, myoclonus, twitching, vertigo. Risk of new-onset seizures. CV:
Vasodilation, hypertension, palpitations, tachycardia, syncope, edema, peripheral edema. GI:
Abdominal pain, diarrhea, nausea, vomiting, increased appetite, mouth ulcers. Respiratory:
Pharyngitis, cough, bronchitis
, dyspnea, epistaxis, pneumonia
Rash, pruritus, alopecia, dry skin, sweating, ecchymoses. Special Senses:
Amblyopia, nystagmus, tinnitus. Urogenital:
Dysmenorrhea, dysuria, metrorrhagia, incontinence, vaginitis
InteractionsDrug: Carbamazepine, phenytoin, phenobarbital
decrease levels of tiagabine. Use with antidepressants
, and narcotics
may increase seizure risk. Herbal: Ginkgo
may decrease anticonvulsant effectiveness. Evening primrose
oil may affect seizure threshold.
Rapidly absorbed; 90% bioavailability. Peak:
45 min. Distribution:
96% protein bound. Metabolism:
In liver, probably by cytochrome P450 3A isoform. Elimination:
25% in urine, 63% in feces. Half-Life:
79 h (47 h with other enzyme-inducing drugs).
Assessment & Drug Effects
- Lab tests: Measure plasma levels of tiagabine before and after changes are made in the drug regimen.
- Be aware that concurrent use of other anticonvulsants may decrease effectiveness of tiagabine or increase the potential
for adverse effects.
- Monitor carefully for S&S of CNS depression.
Patient & Family Education
- Do not stop taking drug abruptly; may cause sudden onset of seizures.
- Exercise caution while engaging in potentially hazardous activities because drug may cause dizziness.
- Use caution when taking other prescription or OTC drugs that can cause drowsiness.
- Report any of the following to the physician: Rash or hives; red, peeling skin; dizziness; drowsiness; depression; GI distress;
nervousness or tremors; difficulty concentrating or talking.